/*
    * Licensed to The Apereo Foundation under one or more contributor license
    * agreements. See the NOTICE file distributed with this work for additional
    * information regarding copyright ownership.
    *
    *
    * The Apereo Foundation licenses this file to you under the Educational
    * Community License, Version 2.0 (the "License"); you may not use this file
    * except in compliance with the License. You may obtain a copy of the License
   * at:
   *
   *   http://opensource.org/licenses/ecl2.txt
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
   * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
   * License for the specific language governing permissions and limitations under
   * the License.
   *
   */
  
  package org.opencastproject.util;
  
  import org.apache.commons.io.input.ProxyInputStream;
  
  import java.beans.PropertyChangeListener;
  import java.beans.PropertyChangeSupport;
  import java.io.IOException;
  import java.io.InputStream;
  
  /**
   * An {@link InputStream} that counts the number of bytes read.
   */
  public class ProgressInputStream extends ProxyInputStream {
  
    private final PropertyChangeSupport propertyChangeSupport = new PropertyChangeSupport(this);
  
    private volatile long totalNumBytesRead;
  
    public ProgressInputStream(InputStream in) {
      super(in);
    }
  
    public long getTotalNumBytesRead() {
      return totalNumBytesRead;
    }
  
    /**
     * Adds a {@link PropertyChangeListener}
     *
     * The listener gets notified as soon as the input stream is read.
     *
     * @param l
     *          the {@link PropertyChangeListener}
     */
    public void addPropertyChangeListener(PropertyChangeListener l) {
      propertyChangeSupport.addPropertyChangeListener(l);
    }
  
    /**
     * Removes a {@link PropertyChangeListener}
     *
     * The listener gets notified as soon as the input stream is read.
     *
     * @param l
     *          the {@link PropertyChangeListener}
     */
    public void removePropertyChangeListener(PropertyChangeListener l) {
      propertyChangeSupport.removePropertyChangeListener(l);
    }
  
    @Override
    public int read() throws IOException {
      return (int) updateProgress(super.read());
    }
  
    @Override
    public int read(byte[] b) throws IOException {
      return (int) updateProgress(super.read(b));
    }
  
    @Override
    public int read(byte[] b, int off, int len) throws IOException {
      return (int) updateProgress(super.read(b, off, len));
    }
  
    @Override
    public long skip(long n) throws IOException {
      return updateProgress(super.skip(n));
    }
  
    @Override
    public void mark(int readlimit) {
      throw new UnsupportedOperationException();
    }
  
    @Override
    public void reset() throws IOException {
      throw new UnsupportedOperationException();
   }
 
   @Override
   public boolean markSupported() {
     return false;
   }
 
   private long updateProgress(long numBytesRead) {
     if (numBytesRead > 0) {
       long oldTotalNumBytesRead = totalNumBytesRead;
       totalNumBytesRead += numBytesRead;
       propertyChangeSupport.firePropertyChange("totalNumBytesRead", oldTotalNumBytesRead, totalNumBytesRead);
     }
     return numBytesRead;
   }
 }